Effect of Additives on the Crystallization Kinetics of Barium Strontium Titanate Glass–Ceramics

Abstract

Barium strontium titanate (BST) has been targeted as one potential ferroelectric glass–ceramic for high‐energy density dielectric materials. Previous testing has shown that the dielectric constant of these materials was as high as 1000 and the dielectric breakdown strength up to 800 kV/cm. This did not, however, result in exceptional energy density (∼0.90 J/cc). In order to increase overall energy density refining agents can be added to the melt, but the nucleation and growth of the ceramic particles can also play a role. Therefore, in this study the crystallization kinetics were studied to more fully understand how BST phase forms so that the optimal energy density could be obtained. It was determined that the activation energy of the crystallization of BST 70/30 glass–ceramic is approximately 430 kJ/mol which is close to the dissociation energy of Si–O bonds. The Avrami parameter was found to be ∼3 meaning that three‐dimensional growth is dominant and the mechanism of growth was interface controlled.

Effect of La2O3 additive on the dielectric properties of barium strontium titanate glass–ceramics

“…An endothermic peak and two exothermic peaks were observed in the DSC patterns, which was corresponded to the temperature of glass transition and crystallizations. The first exothermic peak (T p1 ) was the crystallization temperature of the perovskite phase (BST) [10], while the secondary exothermic peak (T p2 , 1,010°C) corresponded to the crystallization of Ba 2 Al 2 Si 2 O 8 , SrAl 4 O 7 and SiO 2 [4,11,12]. When the content of La 2 O 3 increased to 0.5 wt%, the T p2 increased slightly.…”

Dielectric behavior of perovskite glass ceramics

“…The hysteresis (in Fig. 9) of BST samples increases tremendously with the increase of field due to interfacial polarization [146,147].…”

“…Dielectric constant at 1 kHz versus temperature for BST 70/30 samples, b dielectric constant versus temperature plots and c polarization versus electric field plot for BST 80/20 annealed at 1,200°C for 10 h with 1 mol% BaF 2[146,147] …”

Comparative properties of Sr x Ba1−x TiO3 ferroelectric glass–ceramics prepared by powder sintering and melt casting

“…Much attention has recently been paid to a variety of ferroelectric glass-ceramics, such as (Ba,Sr)TiO 3 , (Ba,Sr)Nb 2 O 6 , and (Pb,Sr,Ba)Nb 2 O 6 [1][2][3][4] owing to their potential applications in high energy storage devices. In energy storage capacitors, the energy density is related to the product of breakdown strength (BDS) squared and dielectric constant.…”